Run flat device for motor vehicle and mounted assembly including it

Belt (34) rigidity exerts lateral- and radial gripping forces (FL, FR) on the contact zone (33a) of the annular sectors (31) when they are mounted coaxially between side walls of the recess (11). The belt holds the annular sectors against one sidewall (11a) and the recess (11), whilst support is derived from the other lateral wall (11b).